In order to clean pollutants such as fine particles on a surface of a wafer, an LCD, a color filter or various glass substrates, there has been proposed various techniques. Particularly, in the semiconductor industry, high-pressure liquid is used independently or used in a state of being combined with brushes to remove the polluted fine particles from a surface of a semiconductor wafer. These processes achieved partial success in removing the pollutant. However, the brushes scratch the surface of the substrate, and also it may generate undesirable static electricity. And, the high-pressure liquid is apt to cut the soft surface of the substrate. Further, the high-pressure liquid has a drawback that it is not easy to withdraw the liquid from the brushes and high-pressure liquid cleaning system.
Meanwhile, it is well known that solid and gas phase carbon dioxide (CO2 snow) can remove the polluted fine particles from the surface of the substrate without the above-mentioned drawback. One of the techniques is disclosed in U.S. Pat. No. 5,125,979.
In the above mentioned technique, there are provided a small expansion chamber and a large expansion chamber which are communicated with each other through a venturi interposed therebetween. At an outlet of the large expansion chamber is provided an accelerating chamber for accelerating an injecting speed of a cleaning medium. The cleaning medium is supplied from a cleaning medium supplying source to the small expansion chamber, and then adiabatically expanded while being supplied through the venturi to the large expansion chamber, thereby forming Co2 snow having snow particles of about 46%. The Co2 snow is accelerated by inert gas introduced to the accelerating chamber, and then injected through a nozzle to a desired position in which the cleaning process is performed.
That is, in the technique, the cleaning medium is transformed into the Co2 snow, while passing through the venturi. Then, the particles of the Co2 snow grow, while the Co2 snow passes through the large expansion chamber. The cleaning medium injected through the nozzle cleans the pollutant on the surface of the substrate and then sublimed.
However, in the technique, since the cleaning medium of Co2 is transformed into the Co2 snow, while passing through one venturi, a solidification rate of the cleaning medium is low. Furthermore, since the cleaning process is typically performed at a high presser, there is a problem that a large quantity of cleaning medium is needed to remove the polluted fine particles under the same conditions.
To solve the problem, the applicant had proposed Korean Patent application No. 2000-8560 filed on Feb. 22, 2000, entitled “Nozzle for cleaning components of semiconductor fabricating equipment”.
As shown in FIGS. 1 to 3, the nozzle for cleaning components of a semiconductor fabricating equipment has first and second venturi blocks 51 and 53, which are disposed in series, to provide a wider cleaning surface than a single nozzle, thereby maximizing the cleaning efficiency. A carrier gas supplying pipe 61 is connected to a base block 55 in which the first venturi block 51 is disposed. A cleaning medium supplying pipe 59 is connected to a sub-block 57 disposed at an upper side of the base block 55.
The cleaning medium supplying pipe 59 is connected to a cleaning medium chamber 13b in which high-pressure Co2 is stored in liquid phase. The cleaning medium supplying pipe 59 is controlled by a regulator 11 to have a lower pressure of 100˜120 psi. Since the cleaning medium of Co2 is reduced from the high pressure to the low pressure, the particles of snow state are formed in the cleaning medium. The cleaning medium controlled to have the above-mentioned pressure is supplied through the cleaning medium supplying pipe 59 and the sub-block 57 to a fan-shaped space 51a formed in the base block 55.
The carrier gas supplying pipe 61 is connected to a carrier gas chamber 13a to supply carrier gas such as N2 to the base block 55. The carrier gas is stored in the carrier gas chamber 13a at a high pressure. As shown in FIG. 2, at an distal end of the carrier gas supplying pipe 61, there is formed a slot 61a for uniformly injecting the carrier gas into a plurality of venturi paths formed at the first venturi block 51. At the sub-block 57, there is formed a path 57a perpendicular to the fan-shaped space 51a to be communicated with the space 51a. The cleaning medium supplying pipe 59 has a circular portion on which the cleaning medium is dashed, so that the cleaning medium is uniformly injected into the fan-shaped space 51a. 
Accordingly, the cleaning medium supplied through the cleaning medium supplying pipe 59 to the space 51a of the base block 55 is mixed with the carrier gas injected from the carrier gas supplying pipe 61 in the space 51a so as to firstly induce the solidification of the cleaning medium. The mixed gas is adiabatically expanded, while passing through the venturi paths formed in the first venturi block 51, whereby a temperature and a pressure of the mixed gas are sharply reduced. Since the cleaning medium is adiabatically expanded in the first venturi block 51, the solidification of the cleaning medium is further promoted. Further, the cleaning medium is adiabatically expanded again, while passing through the second venturi block 53, and thus, the solidification of the cleaning medium is promoted once more. However, the conventional technique as described above has a structure that the cleaning medium supplying path is perpendicular to the carrier gas supplying path at a place where the cleaning medium and the carrier gas is mixed. Therefore, since the carrier gas having the higher pressure than the cleaning medium is flowed back to the cleaning medium supplying path, there is a problem that the cleaning medium supplying path is clogged. Furthermore, since the carrier gas is supplied at the high pressure, there is another problem that the consumption of the carrier gas is increased.